The invention relates to a pushbutton tuner, and more particularly, to a pushbutton tuner having a small assembled size suitable for containment in an enclosure of a limited size, in conjunction with an eight- or four-track tape player.
Efforts have been made to install an audio instrument including both a pushbutton tuner and an eight- or four-track tape player in a limited space such as a standard dashboard box of an automobile which is often utilized for the provision of a car radio set. Such an audio instrument is economically advantageous in that the principal electrical circuit is shared by both the tuner and the player, and also facilitates the operation thereof by a user. However, such effects have not achieved a satisfactory success as yet because of the failure to reduce its size sufficiently to permit its accommodation in a space comparable to the conventional car radio set. As is recognized, an eight- or four-track tape cartridge is standardized in size, so that the associated tape player must be provided with a housing of a predetermined size. If it is installed in a space such as an automobile dashboard box in which a car radio set is normally provided, it occupies a large proportion of the space, with the vertical height thereof reaching substantially one-half that of the dashboard space. The tape player essentially comprises a tape drive which requires a substantial vertical dimension for its provision. In particular, a flywheel which is used to drive a tape capstan is disposed for rotation in a plane which is located above the cartridge housing, thus adding the overall height of the tape player. It will be evident, therefore, that if such a player is disposed in overlying relationship with a conventional pushbutton tuner, the resulting assembly will be too large to be contained in a standard dashboard box.
A conventional pushbutton tuner includes a plurality of manually operated slides, which are formed as flat plates having their major surface disposed in a vertical orientation. Each slides is movable between its inoperative and operative positions independently from each other, and when one of the slides is moved to its operative position, a control member carried thereby is effective to locate a movable part of a tuning element to a predetermined position corresponding to a desired signal frequency to be received. In order to enable tuning to a particular frequency, the control member includes a cam plate which may be positioned relative to the associated slide in a manner corresponding to the desired frequency. The cam plate is normally locked and maintains this position unless it is unlocked. The tuning element includes a rockable arm carrying a pair of parallel rods which are selectively engaged by the cam plates associated with the individual slides, and which are moved by a selected cam plate to cause the arm to operate to a telescoped armature in a tuning coil. The rockable arm can also be adjusted to a position corresponding to a desired reception frequency by a rotatable knob which is manually operated through a clutch. In this instance, when a selected cam plate is unlocked and engaged with the pair of rods, this cam plate can be positioned on the associated slide so as to correspond to the desired frequency. When positioning the cam plate in this manner, the clutch is maintained to continue the operative connection between the clutch is maintained to continue the operative connection between the rotatable knob and the rockable arm, serving to lock the latter in order to avoid any unintended movement of the pair of rods as they are engaged by the selected cam plate. In this manner, a precise positioning of the cam plate is assured which permits a subsequent tuning to the desired frequency. During normal use, when a pushbutton is operated to move one of the slides to its operative position, the clutch is disengaged before the slide reaches its operative position, releasing the rockable arm operatively connected with the driven clutch shaft for free movement. A release member for the clutch comprises a comb-shaped swingable arm which is disposed across the array of slides, and as it is moved together with a slide, it operates a trip lever.
Conventional pushbutton tuners have the disadvantage of requiring an increased vertical dimension even though a substantial wasted internal space is left between adjacent slides. This is due to the arrangement employed in which the individual slides are disposed in vertical orientation and the tuning element or the pair of rods are disposed across the array of slides on the opposite sides thereof. In order to permit an independent operation of pushbuttons which are arranged in juxtaposition, each pushbutton must be spaced from adjacent one or ones by a minimum spacing which is primarily determined by the finger size. It represents an obvious loss of the available space which is at premium not to utilize the unused spaces between the pushbuttons but to dispose the slides in a manner to increase the height. If such loss can be eliminated, there can be obtained a pushbutton tuner of a reduced size without compromising the mechanical strength which would otherwise result from a reduction in the size of mechanical components used.
To allow a horizontal orientation of the slides, there must be provided an alternate tuning element which is substituted for the usual rockable arm which is selectively engaged by cams carried by the individual slides. One proposal has been made previously by one of the present inventors to resolve this problem. Essentially, the proposal comprises the provision of a movable plate which is disposed across the array of slides and which is formed with a plurality of apertures of an isosceles triangle form, one each associated with individual slides which are arranged in horizontal orientation and in juxtaposition. Each aperture engages an upstanding pin secured to a control plate on the associated slide, and when a selected slide is moved to its operative position, the pin shifts the movable plate to a predetermined position. The proposal failed to bring forth a practical implementation, however, because of the difficulty in positioning a control member carried by a selected slide so as to adjust a particular pushbutton to a particular frequency, though a novel tuning element has been proposed. When positioning the control member, the tuning element is locked against movement, and this caused a difficulty in operatively connecting the tuning element with a rotatable knob and controlling the clutch to release the operative connection when a slide is operated. Specifically, no space was available in the proposed construction to install a conventional clutch trip member, and additionally, the use of such trip member resulted in immediately releasing the clutch when depressing the pushbutton from its reset position. However, this prior proposal conceived the possibility to construct a pushbutton tuner of a substantially reduced vertical assembled size since a single movable plate is disposed across the slides which are in horizontal orientation. The invention, therefore, provides a practical implementation of the prior proposal mentioned above.